Norwich kept their Premiership survival hopes alive and almost certainly ended Manchester United's slender title hopes with a shock win at Carrow Road.
Dean Ashton headed Norwich ahead from David Bentley's free-kick and crossed for Leon McKenzie to volley home.
Craig Fleming and Jason Shackell were outstanding in a Canaries defence that thwarted United's subdued strikeforce.
The closest they came was when Wayne Rooney saw his injury-time shot tipped over by Norwich keeper Robert Green.
With their Premiership lives on the line, Norwich showed plenty of spirit and grew in confidence as they put United under pressure, but without creating a clear-cut chance.
United drew the sting from Norwich's early surge with some accurate possession football in midfield.
But although Paul Scholes kept his side ticking along like a metronome, they also failed to carve many openings.
United's cause was not helped when Luis Saha's comeback for the first time since 1 February lasted just 17 minutes before he limped off with what appeared to be a calf problem.
Ashton scored the first and made the second
It was patently a day for patience for United as they pinged the ball around sweetly in an attempt to pull Norwich out of shape.
They failed, though, to offer much support to lone striker Alan Smith who was well policed by Fleming and Shackell.
Having seen his expensively-assembled strike force score just once in their previous three Premiership matches, Sir Alex Ferguson was prompted into action, and decided to throw Rooney up alongside Smith.
But Rooney's first contribution was a costly one for his team.
Not only was he booked for a foul on Darren Huckerby he then saw the punishment doubled as Ashton climbed highest to Bentley's well-flighted free-kick to plant a header past Tim Howard.
Rooney's afternoon took another down-turn when he was muscled out of possession by Youssef Safri and Norwich broke with devastating effect as Ashton delivered an inviting cross for the unmarked McKenzie to volley home from eight yards.
Despite having Rooney, Smith and Ruud van Nistelrooy in the firing line there was a lack of conviction about United in the last third.
All too often they lacked the killer pass to unlock a determined and committed Norwich defence in which Fleming and Shackell were outstanding.
Norwich boss Nigel Worthington:
"It's another win. I said at the start we were going out there to win the game, as we have done all season.
"I had a bit of a gripe in the local press this week about putting their foot in and getting closer to people and credit to the players they did.
"I am pleased that we won convincingly and in style, which is great."
Manchester United reaction:
Boss Sir Alex Ferguson refused to speak to his club's TV station or the press after his side's shock 2-0 defeat at Norwich.
It is the first time in the seven years of MUTV that Ferguson has not shared his post-match thoughts with them.
But full-back Gary Neville told MUTV: "That was not good enough from start to finish. I don't know where to start.
"If we do not score at Norwich and let a couple in, it amounts to an embarrassing day for us."
Norwich: Green, Helveg, Fleming, Shackell, Drury, Stuart (Bentley 45), Francis, Safri, Huckerby (Jonson 86), McKenzie, Ashton (Svensson 84).
Subs Not Used: Ward, Doherty.
Booked: McKenzie, Bentley.
Goals: Ashton 55, McKenzie 66.
Man Utd: Howard, Gary Neville, Ferdinand, Silvestre, Heinze, Kleberson (van Nistelrooy 63), Scholes, Phil Neville, Fortune (Rooney 45), Saha (Ronaldo 22), Smith.
Subs Not Used: Carroll, O'Shea.
Booked: Rooney, Scholes.
Ref: H Webb (S Yorkshire).